The present invention relates to coating compositions for providing corrosion resistance on metallic substances, and more particularly, to such a coating composition that is especially useful for preventing rust and corrosion on vehicle underbodies and interior body parts. Importantly, the composition of the present invention may be used inside frames, on hidden supports and to cover many irregular surfaces which cannot be coated with the typical, more viscous compositions of the prior art. Therefore, the term "underbody" as used hereinafter will be understood to refer to all such parts of a vehicle.
Therefore, although it will be appreciated by those skilled in the art that the coating composition of the present invention may be applied to any type of metallic substrate, whether ferrous or non-ferrous, it is especially suited for use on ferrous surfaces and will be described in connection therewith.
In various areas of the country in which motor vehicle underbodies are subjected to mixtures of moisture and salt, it has become customary to coat the underbody of the vehicle with a protective "undercoating." Conventional undercoatings have been primarily of the asphaltic type, which sets up to form a dry, hard coating which, when it is tightly adhered to the metal substrate, provides fairly satisfactory resistance to rusting and corrosion of the substrate.
One of the more serious disadvantages of the prior art asphaltic-type compositions is their tendency to become brittle, crack and separate from the substrate over local areas, forming a pocket which can trap corrosive salt water and keep it in contact with the metal substrate over an extended period of time.
Another disadvantage encountered with many prior art compositions is the necessity of applying them as a two-part system, with the two separate applied coatings reacting chemically after application. Two-part systems obviously require an excessive amount of labor time and equipment utilization. Therefore, as used herein, the term "one-part", in reference to the composition of the present invention, means one in which all of the necessary ingredients may be combined as one mixture, for application as one coat.